Signaling device



Sept. 25, 1945. (5, E ATKlNs 2,385,339 SIGNALING DEVICE yFiled oct. 2e,194s 2 sheets-sheet 1 46] 22 I6) l5 I6, 35 l? 33 ATTORNEY Sept' 25, 1945G. E. -ATKlNs l 2,385,339

/N VEN To@ @y G. E. A Tlf/NS y ATTORNEY Patented Sept. 25, 1945 UNITEDSTATES PATENT OFFICE SIGNALING DEVICE Application October 26, 1943,Serial No. 507,705

9 Claims.

This invention relates to signaling devices and particularly to suchdevices as employed to gencrate and record telephone call signals in asound powered telephone system.

Sound powered telephone systems are, in general, characterized by theabsence of auxiliary power sources, such as batteries, for furnishingthe power required for the transmission of speech signals. In suchsystems speech signals are generated in the coils of an electromagneticsound powered unit comprising essentially a permanent magnet, a balancedarmature and a diaphragm coupled to the armature. In a transmitter unitthe diaphragm is acoustically actuated by speech signals impinging onthe diaphragm and the armature is correspondingly vibrated in the fieldfurnished by the permanent magnet to cause the generation of speechfrequency currents in the coils. Conversely, in a receiver unit speechfrequency currents applied to the receiver coils cause the armature andits coupled diaphragm to vibrate at the frequency of the incomingsignals to produce audible speech signals.

Such systems are lacking in complete simplicity in that the transmissionof telephone call signals1 requires the use of auxiliarybatteries forthe energization of the call indicator, particularly where it isdesirable that the manifestation of an incoming call persist indenitelyand until such time as the call is answered at the called station. In aparticular system of this character, a visual signal in the nature of anelectronic tube is employed as a call indicator and responds to thetransmission of an acoustic signal of a level higher than the level ofspeech signals to visually indicate the arrivai of an incoming call.Such a call signal requires a biasing Voltage, furnished by a battery,not only to eiect its operation but also to maintain it locked operateduntil extinguished by some act on the part of the subscriber at thecalled station or of an opera-tor at an exchange.

It is the object of this invention to provide an improved combinedaudible and visual signal device which functions without the aid ofbatteries or other auxiliary source of power to furnish a permanent callsignal in a sound powered telephone system.

This object is attained in accordance with a feature of the invention bycombining, in a unitary structure, a visual signal indicator, in thenature of an annunciator drop, and an audible signal device, in thenature of a vibratable gong, and by placing the operation of bothdevices under the single control of an ultra-sensitive electromagneticsystem consisting essentially of a -coil and a balanced armature systemincluding pole-pieces, permanent magnet means for producing a iluxbetween the pole-pieces and an armature vibratable in the air gaplocated between the pole-pieces.

More particularly, the combined visual and audible signal device of thisinvention embodies an electromagnetic system of the type dened abovewhose armature is loosely coupled to a latch bar and when vibratedcauses the latch bar to release a gravity operated mechanism, whichcombines an annunciator drop signal, or target, and the striker for avibratable sound emitting device in such a manner that the target isoperated as a visual signal and the sound emitting device issimultaneously actuated as an audible signal.

Another feature of the invention resides in mechanically coupling thesound emitting device with its operating unit whereby the unitfunctions, in response to the Vibrations of the sound signal, as aninertia type transmitter to provide an answer-back signal in a soundpowered tele- `phone system.

In systems of the general character described above the call signal isinitiated at a calling station either by shouting into the telephonetransmitter or by slapping the transmitter mouthpiece. Either operationserves to compress the air in the cavity in front of the diaphragm withwhich such transmitters are equipped, causing the diaphragm to move backand swing the attached armature far off center in one direction. Thisaction induces a surge of current in the coil surrounding the armature.The armature in snapping back overthrows center and induces a secondsurge in the coil in the opposite direction. In order to simplify thegeneration of such call signals the telephone handset employed in asystem in which the combined visual and audible signal device of thisinvention is used to particular advantage, is equipped with a manuallyoperable button which functions, through a plucking mechanism, todirectly agitate the receiver diaphragm and thus generate, in thereceiver coils, a call signal of sufficient intensity to actuate thecombined visual and audible signaling device as a call indicator.

These and other features of the invention will be readily understoodfrom the following description when read in connection with theaccompanying drawings, in which:

Fig. 1 is a View of the ultra-sensitive signal device taken along theline I-I of Fig. 2, looking in the direction of the arrows, and showsthe target, or drop which constitutes the Visual signaling element;

Fig. 2 is a top plan view of the signal device;

Fig. 3 is a view of the signal device taken along the line 3--3 of Fig.2, looking in the direction of the arrows;

Fig. 4 is an outline view of the receiver portion of a sound poweredtelephone handset showing the diaphragm actuating mechanism and itsoperating button;

Figs. and 6 are detail views of the dlaphragm actuatingmechanism showingthe same in its normal and operated positions, respectively; and

Fig. '7 is a circuit diagram showing schematically a sound poweredtelephone handset located at the calling end of a line and theultra-sensitive call signal device located at the answering end of theline.

The basic element of the signaling device shown particularly in Figs. 1,2 and 3 and schematically in Fig. '7 is an electromagnetic systemcomprising essentially a coil and a balanced armature system includingpole-pieces, permanent magnet means for producing a flux between thepole-pieces and a vibratile armature. This element is mounted on a baseplate I3 preferably of a non-magnetic material such as brass andcomprises a pair of substantially identical U-shaped magnetic members I2and a pair of similar short bar magnets I3. Each of the magnetic membersI2 comprises a rpair of parallel pole tips or anges I4 and arms I5extending from opposite sides of the tip's or flanges I4. The arms I 5abut opposite ends of the magnets I3 which space the members I2 inparallel relation, with the tips or flanges of one member I2 oppositeand aligned with those of the other whereby two identical air gapsareformed. Like poles of the magnets I3 abut the same magnetic member I2 sothat two magnetic circuits of substantially the same reluctance andmagnetomotive force having a common branch through the pole tips I4 andthe air gaps are formed.

The ends of the magnets I3 are ground so that air gaps of the desiredlength are formed between juxtaposed pole tips I4. The magnetic membersI2 are securely clamped against the magnets i3 by non-magnetic bolts I5which extend through apertures in the base plate I0. Preferably, themagnets I3 vare provided with longitudinal grooves I'I as shown in Fig.2, in which the bolts I6 are fitted and thereby position the magnetswith respect to the plate I0.

Extending between the pole tips I4 with its ends located in the air-gapsbetween juxtaposed pole tips I4 is a magnetic armature I8 which ispivotallsr mounted at its center between non-magnetic supports I9 andhas one end aiixed to the connecting pin or rod 20. The supports I9,which may be, for example, phosphor bronze strips notched at theiradjacent ends to engage the sides of the armature are fitted into slots2| in parallel non-magnetic support blocks 22 and are locked in theslots as by screws or bolts 23. The blocks 22 in turn are alixed to thelower magnetic member I2 by screws 24 threaded into the blocks.

The armature I8 is encompassed by a pair of coils 25 carried byinsulating forms or bobbins 23 positioned between the flanges or poletips I4. Electrical connection may be made to the coils 25 throughsuitable conductors.

Fixed in any suitable manner to the upper magnetic member I2 is abracket 39 having a pair of oppositely disposed upturned projectionswhich are apertured to receive the rod 3I. The rod 3| passes through alatch bar 32 and provides a pivot bearing therefor. At its right end,viewing Figs. 2 and 3, the bar 32 is provided with a bore or holethrough which the free end of rod or pin 2i) extends. The upper end ofthe rod 2i) is flared slightly and is provided with a fixed collar 33 sothat the rod 29 may experience an upward thrust,

viewing Fig. 3, without influencing the latch bar 32 but when pulleddownward it will cause the latch bar 32 to pvot on the rod 3| to causeits forward end to be raised.

The latch 32 is notched near its forward end to receive the upper edgeof a weighted element 34 and to thereby retain the element 34 in itsnormal unoperated position shown in Fig. 3. The weighted element 34 hasfixed thereto, in any suitable manner so as to project outwardlytherefrom, a clapper rod 35 which carries at its end a striker 3B. Theelement 34 is carried by and xed to the rod 31 which has one endsupported by a set screw 38 carried by an extension 39 of the plate Iand its other end passing through an aperture in a similar oppositelydisposed extension 49 of plate I9.

The rod 3'! carries a collar 4I which is fixed to the rod and abuts theinner surface of the plate extension 48. Fixed to the collar 4I is a rod42 which carries a target 43. The target 43 normally assumes a positiondirectly in back of the circular hole 44 located in the plate extension40. Near its outer end the rod 31 carries a pin or handle 43 which, aswill be described hereinafter, is manually operable to reset the target.

Aixed to the under-side of the plate Il) is a gong 48 which may besecured to the bolt 49 by means of a nut 5l). The bolt 49 itself isscrewed into a threaded hole in the plate I0. By virtue of this mountingthe gong is mechanically coupled to the electromagnetic unit for apurpose to be indicated hereinafter. The gong is so positioned relativeto the clapper rod 35 and its striker 36 that when the weighted elementis actuated, as will be described presently, the striker 36 contacts thegong causing it to vibrate. To permit the clapper rod 35 freedom ofmovement, the plate I 0 is slotted at 55 and the inner edge of this slotis so disposed relative to the edge of the gong that the striker 36statically clears the gong after having struck it, thus allowingundamped vibrations of the gong.

When the coils 25 are energized, the armature I8 is vibratedk and.through the loose coupling effected by the connecting rod 20 the latchbar is actuated and pivots about the rod 3|. The forward end of thelatch is thus raised causing the release of the weighted element 34which rotates, under the action of gravity, with the rod 35 in acounter-clockwise direction as viewed in Fig, 3. The striker 36,accordingly, impinges against the gong 48 causing the latter to vibrateand emit an audible tone. The shaft 31 in rotating carries with it thetarget 43 so that it is removed from its normal position in back of theaperture 44. It will be understood that, in practice, a plurality ofsuch devices would be mounted on a switchboard and the disappearance ofthe target would identify the particular line calling. If desirable thegong may bevmade common to a plurality of such devices to function as acornmon audible signal in conjunction with a plurality of individualline identifying visual signals.

In Fig. 4 there is disclosed a sound powered unit of substantially thesame type disclosed in Figs. 2 and 3 and mounted in the receiver portionof a telephonehandset. The unit disclosed in Fig. 4 distinguishes fromthat shown in Figs. 2 and 3 principally in that a diaphragm 6D is Xed tothe connecting rod 2U in place of the latch bar 32. Suffice it to saythat when the diaphragm is agitated, the armature I8vis vibrated causingan electromotive force to be generated in the coils 425', As a means foragitating the diaphragm 60 there is disclosed a plucking mechanismcomprising a reed spring 62 which is arched at its center and has eachof its ends turned in and secured to the supporting bracket 63 by rivets64 or by any other suitable means. At one end` of the spring there isintegrally formed a plucking finger 65. As shown in Fig. 5, the hookedend of the nger 65 is normally located opposite and below the end of aprojection 66 iitted to the diaphragm 69. A button 61 which protrudesthrough an aperture in the handset casing 68, as shown in Fig. 4, hasits operating end abutting the spring 62 at the apex of its arch. Whenthe button is depressed by the thumb of the party employing the handset,the spring 62 assumes the position illustrated in Fig. 6. During thetransition from normal to operated positions the inclined end of theplucking finger 65 is raised to the position shown in i Fig. 6 and inmoving to this position it passes over the edge of the projection S6causing the diaphragm to be agitated. When the button 6'! is released itis restored to normal by the action of spring 62 in resuming its normalunactuated condition. In snapping back to its normal position the nger65 again agitates the diaphragm 60 through the projection 66.

The E-shaped member 68 mounted on the bracket 63 has a central portionwhich serves as a stop for the button 61 and limits its downwardmovement. The two outer portions insure uniformity in the operations ofthe spring as well as correct action of the plucking linger 65 on thediaphragm projection 66. .In locating the projection 56 on the diaphragmconsideration must be given to the desired intensity of the call signal.In aixing the projection substantially midway between the corrugations'l0 of the diaphragm 53 and its support at 'Il the diaphragm is agitatedsufliciently to produce a signal of average intensity. If a greaterintensity is desired the point of attachment of the projection E6 wouldbe closer to the corrugated portion of the diaphragm and further removedfrom the support 1I.

The button 61 is provided with a collar 'l2 which abuts the rim of theaperture through which the shank of the button protrudes from the casingand is normally held in this position by the action of spring 62. Thebracket 63 is secured to the receiver unit by screws 18. f

Referring now to Fig. '7, the line L is shown terminating at tworemotely separated points in jacks J1 and J2. The jack J1 may be locatedat a calling station and the jack J2 at a central switchboard. When itis desired to communicate with the central station over line L the partywhose station is equipped with the handset S would connect the set tothe line by inserting plug P into jack J1 and then depress the button 6l`and release it. The diaphragm 66 is thus agitated in the mannerhereinbefore described and a corresponding current generated in thecoils This current traverses the line L by way of the normal contacts ofpush to talk key H and the contacts of plug P and jack J1 and energizesthe coils 25 of the combined audible and visual signal D at the centralofiice. The armature i3 vibrates at the frequency of the currenttraversing the coils and actuates the latch 32 in the manner previouslydescribed. The weighted member 34 is thereby released and falls, due tothe action of gravity, to the position indicated by the dash-dot outlineshown in Fig. 3.

The gong 48 is struck by the striker 36 and the target 43 moved to anindicating position.

It will be observed that due to the loose coupling of the armature I8and the latch 32 as effected by the connecting pin 20, the latch will beactuated on the iirst surge of current if of a polarity such as to causethe armature to pull the connecting pin 2|] downwardly, viewing Fig. 3.However, if the first current surge is of the opposite polarity the pin28 moves freely in the hole in the latch 32 and will function on thesecond current surge to actuate the latch. Thus it is unnecessary topolarize the call signal indicator so as to render it operative on aparticular polarity of incoming current and no undue strain is placed onthe armature or on the connecting pin should the polarity of the firstcurrent surge be such as to move the pin upwardly, viewing Fig. 3.

Due to the mechanical coupling of the gong with the call indicator unitthe vibrations of the former when actuated are transmitted to theindicator unit causing it to function as an inertia type transmitter andthe voltage resulting from the reverberations of the gong and induced inthe coils 25 is transmitted back over the line L to the receiver of thetelephone set S at which the call signal was initiated. The receiverunit responds' to this voltage to produce an answer back signal as anindication that the call signal has been successfully recorded at thecalled station.

As previously described, the plate I0 is slotted at 55 to allow freedomof movement of the clapper rod 35 to and from its actuated position. Therod 35 when actuated strikes the back edge of the slot 55 and isdesigned to have sufficient weight and flexibility to continue in itsmovement towards and to strike the gong and then to come to rest in aposition in which the striker 36 statically clears the gong. This staticclearance precludes the striker resting against the gong and damping itsvibrations after it has been struck.

After receipt of the combined audible and visual call signal, theoperator at the central station .would restore the signal unit to normalunoperated condition by rotating the hand lever l in a clockwisedirection thereby rotating the shaft or rod 3l and the associatedclapped rod and target to normal positions. In this position the edge ofthe weighted member 34 reengages the groove or slot near the outer endof the latch 32 and is thereby maintained in its normal restoredposition. The call may be answered in the usual well known manner.

After the calling subscriber has received the answer back signal, asabove described, the button il may be actuated to eiifectively removethe coils 25 of the receiver unit from the line and the transmitter unitutilized for the transmis- A sion of speech signals over the line L.

The telephone set S has been illustrated as equipped with a plug endedcord for associating the set with-the line L. It will be understood thatthe connection of the set to a line may be made by the regularswitchhook contacts which are housed within the stand or cradle supportusually provided for supporting the yhandset It will also be understoodthat when the line L is seized at the central station in response to theactuation of the combined audible and visual signal device D the circuitto the coils 25 is opened at the jack contacts 19 to effectively removethe` coils from the line during the transmission of speech signals.

What is claimed is:

1. The combination, in a signalling device, of a sound emitting device,a striker therefor, gravity operated means for Vcontrolling theoperation of said striker, a latch normally maintaining said gravityoperated means in restrained position, and means for actuating saidlatch to release said gravity operated means comprising anelectromagnetically operated device including a balanced armature, andmeans comprising a connecting pin loosely coupling said latch and saidarmature.

2. The combination, in a combined audible and visual telephone callindicating apparatus, of a sound emitting device, a target indicatorhaving a normal display position, a striker for said sound emittingdevice, a rod supporting said target indicator and said striker, aweighted element carried by said rod and adapted, when released, torotate said rod to cause said striker to actuate said sound emittingdevice and said target indicator to be moved from its4 normal position,a latch normally engaging said Weighted element and holding it in arestrained position, and means for actuating said latch comprising anelectromagnetic system including a balanced armature, and a connectingpin fixed to one end `of said armature and loosely associated with saidlatch.

3. The combination deiined in claim 2 wherein manually operable means ismounted on said rod for restoring said striker and target indicator tonormal positions.

4. The combination, in a call indicator, of a sound emitting device, astriker therefor, and an electromagnetic system for actuating saidstriker including a base-plate, an electromagnetic unit mounted on saidbase-plate comprising a pair of permanent magnets having oppositelydisposed juxtaposed pole-pieces, an armature pivotally mounted at itsmid-point so that its extremities extend into the air-gaps effected bysaid juxtaposed pole-pieces, a coil encircling said armatureresponsiveto alternating current for vibrating said armature, means controlled bysaid armature, when vibrated, for causing said striker to actuate andvibrate said sound emitting device, and means mechanically coupling saidsound emitting device to said electromagnetic unit whereby said unitfunctions in response to the vibrations of said sound emitting device asan inertia type transmitter and a current, corresponding in frequency tothe frequency of vibration of said sound emitting device, is developedin said coil.

5. In combination, an armature, an electromagnetic unit comprising acoil and a magnetic circuit including air-gaps in which said armaturevibrates upon the application of alternating current to said coil, saidunit being vibratable relative to said armature to cause a current of afrequency, corresponding to the frequency at which said unit isvibrated, to be developed in said coil, and means for vibrating saidunit relative to said armature comprising .a vibratable sound emittingdevice mechanically coupled to said electromagnetic unit, and means forvibrating said sound emitting device.

6. In combination, an armature, an electromagnetic unit comprising acoil and a magarmature vibrates upon the application of alternatingcurrent to said coil, said unit being vibratable relative to saidarmature to cause a current of a frequency, corresponding to thefrequency at which said unit is vibrated, to be developed in said coil,and means for vibrating said unit relative to said armature comprising avibratable sound emitting devict,` mechanically coupled to saidelectromagnetic unit, and means for vibrating said sound emitting devicecomprising a striker controlled by said armature.

7. The combination, in a combined audible and visual signaling device,of a vibratable sound emitting device, an annunciator target having anormal display position, a striker for vibrating said sound emittingdevice, common means supporting said striker and said annunciatortarget, gravity operated means for controlling the operation of saidcommon means, means comprising a latch for maintaining said gravityoperated means in a normal restrained position, land means for actuatingsaid latch to cause the release of said gravity operated means whereuponsaid striker engages said sound emitting device and said annunciatortarget is moved from its normal position, comprising a vibratablearmature, alternating current responsive means for vibrating saidarmature, and means loosely coupling said armature and said latch.

8. In combination, in a signaling device, a vibratable sound emittingdevice, means for actuating said sound emitting device, anelectromagnetic unit including a coil and a vibratable armature, saidcoil being responsive to alternating current rfor vibrating saidarmature, means responsive to the vibration of said armature for causingsaid actuating means to vibrate said sound emitting device, and meansmechanically coupling said sound emitting device and saidelectromagnetic unit whereby the vibrations of said sound emittingdevice are transmitted to said electromagnetic unit to cause thegeneration in 'said coil of a current of a frequency corresponding tothe frequency of vibration of said sound emitting device.

9. In a combined audible and visual call indicating apparatus, avibratable gong, a striker for vibrating said gong, a target, arotatable rod xedly supporting said striker and target, gravity operatedmeans for rotating said rod to cause said striker to strike said gongand said target to assume a signal displaying position, said gravityoperated means being fixed to said rod, a latch normally engaging saidgravity operated means so.as to hold said rod in a restrained position,and means for actuating said latch to release said gravity operatedmeans and thereby cause said rod to be rotated comprising anelectromagnet having juxtaposed flux producing permanent magnet poles,an armature mounted at its midpoint so that its extremities assumepositions between juxtaposed poles of said electromagnet whereby saidarmature is normally held in a condition of balance by the permanentmagnet ux, and a coil encircling said armature and responsive toalternating current to cause said armature to oscillate, and meanscoupling said armature and said latch in such a manner that saidarmature when actuated in one direction moves independently of saidlatch and when moved in the opposite direction functions to actuate saidlatch.

GEORGE E. ATKINS.

